Electrical power distribution may be distinguished as providing transport over radial and interconnected networks. Radial networks spread outwards from a station without interconnection to other supplies. Each node receiving electrical power through a radial distribution network uniquely receives power from a single power station and that power is transmitted through only a single path in the distribution network. Radial distribution networks may be particularly common in rural areas, which are served by long distribution lines serving a sequence of isolated areas. Interconnected networks contains interconnections between lines of distribution. A node receiving electrical power through an interconnected distribution network may receive or be able to receive power from two or more power stations and may receive or be able to receive power transmitted through more than one path in the distribution network. Interconnected networks may be particularly common in urban areas, which are served by dense distribution networks with multiple points of interconnection.
Power flow study, also known as load-flow study, is the application of numerical analysis to a power system to analyze it in normal steady-state operation. The goal of a power flow study is to obtain complete voltage angle and magnitude information for each bus in a power system for specified load and generator real power and voltage conditions. Once this information is known, real and reactive power flow on each branch as well as generator reactive power output can be analytically determined. Due to the nonlinear nature of this problem, numerical methods are employed to obtain a solution that is within an acceptable tolerance. A three-phase power flow study is usually applied to distribution systems where the three-phases are not balanced and have to be modeled independently.